My comments after the playtest tonight:
Great setting and great map so far! Found it a little difficult to "play" and "playtest" at the same time cos I kept on getting killed when I stopped paying attention to the action and thought more about the map! Anyway,
1) The water texture is absolutely gorgeous and fits the cruise setting perfectly. Is that a custom one or is it just a tf2 one and the lighting makes it look so good? On a related note, I wish you didn't die in the water, I wanted to go for a swim! You could maybe think of putting some secret entrance to the ship accessible only from the water outside to justify a little dip once in a while.
2) The brushwork in general is great, I didn't think you could make such good lifeboats from brushes. As others have said you should probably convert them to models as you start finishing your map. I think it's quite easy to do. The portholes are great, but I think you should make them round rather than hexagonal. Again for now just have brushes and you can convert them to models later.
3) The steps in the stairs looked and felt (very jittery) much too big, maybe 2x too big! I think the max you can make stairs is about 8 units high and even then you definitely need player clips to smooth them out.
3) I liked the general layout and the variation, but I feel that for a ctf map it's a bit too big? I also felt that there weren't enough ways to flank, unless you were jumping as demo or soldier. Maybe you could shrink the pool room? (love the pool though).
4) There was a stack of barrels somewhere, which you could jump up on, but for some reason couldn't go over completely even though it looked like you could.
5) Finally, there were one or two places (I think it was your map) where I got caught on brushwork that stuck out a litttle. I think it was near some stairs, and the probable cause was that the brushwork wasn't properly aligned to the grid.
Overall, i only had a short time to play your map so please take these comments as quick first impressions. I think you've done a cracking job so far, so well done and I'm really looking forward to seeing this one completed.